This invention relates to a leveling system for use with a vehicle, such as a recreational vehicle.
Various systems are known for leveling a vehicle such as a recreational vehicle. Some such systems are shown in U.S. Pat. Nos. 4,061,309; 4,165,861; 4,597,584; 4,743,037; and 4,746,133. These patents all show a leveling system having four jacks located one adjacent each corner of the vehicle. Schneider et al U.S. Pat. No. 5,176,391, owned by the same assignee as the present application, discloses a vehicle leveling system having three jacks, two of which are located at the rearward end of the vehicle and one of which is located at the forward end of the vehicle.
Generally, all of the above-noted patents disclose vehicle leveling systems which are relatively complex in construction and operation, to provide automatic leveling of the vehicle in response to certain operator commands.
It is an object of the present invention to provide a manually operated vehicle leveling system which is relatively simple in its components, installation and operation. A further object of the invention is to provide a unique jack construction which is especially suitable for use in a vehicle leveling system such as is contemplated by the invention.
In accordance with one aspect of the invention, a vehicle leveling system includes a series of extendible and retractable jacks mounted to the frame of the vehicle, a manually operated actuator mechanism located within the vehicle interior, and a power system interposed between the jacks and the manually operated actuator mechanism for selectively extending and retracting the jacks. The series of jacks includes first and second jacks located toward one end of the vehicle and a third jack located toward the opposite end of the vehicle. The manually operated actuator mechanism includes a series of switches disposed in a diamond pattern relative to the longitudinal axis of the vehicle. The switches may be in the form of four manually actuated switches mounted to a panel located in the interior of the vehicle. A level sensing device is located in the vehicle interior to provide a visual indication to the operator of the attitude of the vehicle relative to level.
Each jack is preferably in the form of a hydraulic cylinder assembly including a cylinder and an extendible and retractable piston mounted to the cylinder. A spring is interposed between the cylinder and the piston. Introduction of pressurized fluid into the cylinder causes extension of the piston against the force of the spring, and the spring causes retraction of the piston when fluid pressure within the cylinder is relieved. A shoe is connected to the extendible and retractable piston, and the spring is preferably interconnected between the cylinder and the shoe. The power system is preferably a fluid power system consisting of a hydraulic fluid reservoir, a pump for selectively supplying fluid under pressure to the jacks from the reservoir, and a control valve interposed between the hydraulic fluid reservoir and each jack. Each control valve controls the supply of pressurized fluid to one or more of the jacks during operation of the pump, and also provides flow of fluid to the reservoir when the pump is not operating. The control valves are responsive to operation of the manually actuated switches for selectively adjusting the attitude of the vehicle relative to level in response to manual actuation by the operator. Each control valve is interconnected with a single return line interconnected with the reservoir, and a return control valve is disposed in the return line for controlling flow of fluid from the jacks to the reservoir. The return control valve is responsive to a manually operated retract switch actuable by the operator and located within the interior of the vehicle.
The invention further contemplates a unique jack construction for use in the vehicle leveling system of the invention. A plate is interconnected with the hydraulic cylinder of each jack toward the upper end of the cylinder. The spring is interconnected between the plate and the piston, preferably having its lower end mounted to the shoe to which the piston is connected. A connector arrangement is interposed between the spring and the plate for securing the spring to the plate. The connector arrangement is preferably in the form of a tapered passage provided in the upper end of the spring, which decreases in transverse dimension in a bottom-to-top direction, a plug having a tapered wall disposed within the tapered passage and engaging the spring, and a connector extending between the plate and the plug. The plate is mounted to the upper end of the cylinder so as to be selectively pivotable relative thereto. In this manner, the spring can be placed in any desired position relative to the vehicle frame once the cylinder is mounted to the frame in order to avoid any obstructions which may be present in the vicinity of the frame.